1. Field of the Invention
The present invention relates to a medical implantable lead for monitoring and/or controlling of an organ inside a human or animal body, the lead being of the type having a helix in a distal end which is rotatable by means of an inner wire coil, which is disposed inside of and along essentially the hole length of the lead and which is rotatably arranged in relation to an outer sleeve, such that the helix is attachable to the organ by being screwed into the tissue inside the body, wherein the lead is provided with a connector in a proximal end which is connectible to an electronic device for monitoring or controlling the function of the organ, the connector having a connector pin that is in engagement with the wire coil and that is rotatably journaled inside a connector housing such that, during mounting of the medical implantable lead to the organ, the inner wire coil is rotatable by rotating the connector pin in relation to the connector housing by means of a suitable tool.
The invention also relates to a method for mounting a medical implantable lead to an organ inside a human or animal body.
2. Description of the Prior Art
Medical implantable leads for monitoring and/or controlling of an organ inside a human or animal body, are well known in the art, e.g. medical implantable leads for monitoring and controlling the activity of a human heart, which are adapted to be attached to the heart in the distal end and is connected to a pacemaker or an implantable cardiac defibrillator in its proximal end. A common type of such leads is attached to the organ by means of a helix, which is screwed out from the distal end and into the tissue. One way to perform the rotation of the helix is by means of a rotatable inner wire coil, which is located inside and extended along the whole length of the lead. The inner coil is connected to the helix in its distal end and to a connector pin at a connector in its proximal end which projects from the distal end and is rotatably journaled in a connector housing. The connector is adapted to subsequently be connected electrically to the electronic equipment, wherein the inner coil is utilized as an electrical conductor with the connector pin electrically connected to the equipment and the helix as an electrode inside the tissue. However, during mounting of the lead, the projecting connector pin and the inner coil is used to rotate the helix, by means of a suitably tool, to thereby accomplish screwing in of the helix into the tissue and attachment of the lead.
However, the inner coil has a considerable inherent resilience, which has to result that the physician performing the rotating of the inner coil can not sense when the helix is completely screwed out from the lead. Therefore it is common practice to count the number of turns the connector pin is rotated until it is predetermined to be completely screwed out, and subsequently add a few additional turns of rotation to be sure that the helix really is completely screwed out. This has the effect that a tension will be built up in the inner coil from the moment when the helix is completely screwed out until the rotating is terminated after the additional few turns of rotation. When accordingly the physician releases the tool from the connector pin, it often happens that the inner coil spins back and the speed and the mass inertia of the rotational movement of the inner coil may result in that the helix is wholly or partly screwed out and released from the tissue again. Naturally, if this happens it has to be rectified which will increase implantation time and cause frustration to the physician.